Written by Sayyid Ali son of Tāwūs Hussainī Hillī, known as Sayyid Ibn-e Tāwūs (passed away in 664 Hegira)
This book has the same subject as the book Al-Yaqīn' which is to prove that the title of Amīr-ul-Mu'minīn (the Lord of the Faithful) is specified for Hadhrat-e Ali (A.S.) by the Holy Prophet of Islām (S.A.); a title exclusively stipulated for Imām Alī (A.S).
The author states in the introduction: "After compiling Al Yaqīn' I came across about fifty Hadīths (Traditions narrated from the Holy Prophet or His Ahl-ul-Bayt A.S.) whose contents were similar to Al-Yaqīn' but their sources were different. To preserve them from getting lost and safeguard them for the generations to come, I decided to collect them (in a separate book) lest I be blameworthy in the Day of Resurrection".
The author has emphasized that his intention of writing Al-Tahsīn has been protection of Hadīths of the book Nūr-ul-Hudā' from getting lost; therefore, Al-Tahsīn may be considered as a complement to the previous book Al-Yaqīn'. Accidentally all copies of Nūr-ul-Hudā are already lost and the book Al-Tahsīn' is the only documentation for its contents.
1-The older an author, the more valuable his writings are. Age is a factor that develops knowledge, specialty and experience of the writer to the highest level. This book is among the last compilations of Sayyid Ibn-e Tāwūs, which was written after Al-Yaqīn'. Sayyid wrote Al-Yaqīn' at the age of seventies (he passed away at the age of seventy-five).
2- Another factor in distinguishing the authenticity of this book is the character of its author, because as regards his virtue, piety, and reliability, Sayyid Ibn-e Tāwūs did enjoy the highest position among Ulamā (Islamic scholars), and nobody can deny his knowledge and scientific position.
3- Dignitaries like Allāmah Majlisī - with full confidence - have narrated Hadīths of Al-Yaqīn' and Al-Tahsīn' in Bihār-ul-Anwār and their other books.
Apart from slight differences on a few last Narrations of the book, the whole book of Al-Tahsīn is copied from Nūr-ul Hudā wal-Munjī Min-ar-Radā' (written by Hassan son of Abī Tāhir Jāvābī).
Al-Tahsīn' consists of two chapters:
1- A chapter including Hadīths on the subject of naming Imam Ali (A.S.) as Imam-e Kull-e Mu'min' (the Leader of all Faithful Believers) as well as his other titles. This chapter includes 29 units, each of which evidenced by a Narration. Unit 29 includes the complete Khutbah (sermon) of the Holy Prophet (S.A.) in Ghadīr Khum'.
2- The second chapter includes Hadīths about naming Imam Ali(A.S.) as Imām-ul-Muttaqīn (the Leader of all Pious People), and consists of 27 Narrations in 27 units. The last unit is a lengthy Narration about Imām Ali's debates with Jāthelīq religious dignitary of the Jew and his conversion to Islam. During this debate the story of As-hāb-e Kahf' (the Seven Sleepers of Ephesus Cave) is narrated by Amīr-ul-Mu'minīn Ali (A.S.).
One of Ibn-e Tāwūs's skills in this book is leaving some pages blank at the end of the chapter so that in case of finding new Narrations, they could easily be added. Thus, he has eliminated the probability of missing narrations during time.
The original copy of Al-Tahsīn' existed until the era of Sāhib-e Rīyādh (the author of the book Rīyādh').
Al-Tahsīn' and Al-Yaqīn' are beautifully printed in an appropriate size. Hujjatul-Islām Ansārī has made a very interesting research on the book and added an introduction to it. Also at the end of the book there are several indexes available.